This invention relates to a solar energy collector, and more particularly to a flat plate solar collector which effects the efficient collection of solar energy and which is economical to manufacture, utilize and maintain.
In recent years there has been intensive activity in the area of solar energy collection system design. The devices of the prior art succeed to varying degrees in capturing a portion of the sun's energy for use in the heating of water or for other purposes. Often, however, problems of system inefficiency, complexity, high initial costs, high maintenance expenses, excessive weight and short useful lives have offset the advantages to be gained from the devices.
One category of the prior art encompasses collectors incorporating curved collector and/or reflector surfaces. Representative of this group are U.S. Pat. Nos. 3,179,105; 3,923,381; 3,974,824; 4,002,499; 4,088,116; 4,214,573; British Pat. No. 325,179; and French Pat. No. 2,352,260. The designs of these collectors are advantageous in that the curved collector or reflector surfaces concentrate the amount of solar radiation impinging upon the collector element surfaces. A price must be paid for this enhanced efficiency, however, in the form of increased fabrication costs in the production of the curved elements, and increased installation expenses in the calibration and tracking of such complex elements.
A second prior art category includes devices that maintain optimum alignment of the collector surfaces regardless of the sun's position, through the use of tracking systems. Illustrative of these inventions are U.S. Pat. No. 509,393 and German Pat. No. 26 20 469. The principal drawbacks of these systems are higher cost, substantially greater complexity, and considerable system maintenance expense.
A third approach is exemplified by the disclosures of U.S. Pat. Nos. 3,841,302; 4,077,391; 4,122,833; 4,127,104; 4,329,978; French Pat. Nos. 2 379 776 and 2 419 477; and German Pat. No. 30 02 852. In general, these devices utilize relatively simple non-tracking flat plate collector elements. However, only one side of the collector element receives solar radiation, leading to low collector efficiency. Furthermore, the space behind the non-insolated collector surface must be heavily insulated, to reduce heat losses.
Systems have also been disclosed for reflecting incident solar radiation from planar reflectors onto the opposite faces of a collector element. One such system is described in U.S. Pat. No. 4,136,674, wherein solar radiation is reflected from plural planar reflectors onto the successive faces of a central collector or absorber tower, as a boat supporting the reflecting surfaces is rotated about the tower. The design of this and similar systems is, however, relatively complex, imposing substantial capital, installation and operating costs, and substantial maintenance problems.
It is among the objects of the present invention to provide a simple, low maintenance, inexpensive and effective means for circumventing many of the problems of the prior art, for the efficient collection of solar energy.